Percussion-type drill



Aug. 21, 1962 P. P. CAREY PERCUSSION-TYPE DRILL 3 Sheets-Sheet 1 Filed Dec. 30, 1960 Pau/ Pf Cary INVENTOR.

AffQ/P/VEV z 5 a a} y h wiwm y ZR Aug. 21, 1962 Filed Dec. 50, 1960 P. P. CAREY PERCUSSION-TYPE DRILL 5 Sheets-Sheet 2 P00/ f. Carey INVENTOR.

Aug. 21, 1962 P. P. CAREY PERCUSSION-TYPE DRILL 3 Sheets-Sheet 5 Filed Dec. 30, 1960 Pau/ P. (0/ 6y INVENTOR.

ATTORNEY United States Patent Paul P.

This invention relates to percussion-type drills for use in drilling holes in the earth and more particularly to percussion-type drills actuated by pneumatic pressure fluids.

Conventional pneumatic fluid actuated percussion drills all employ generally similar arrangements of an anvil member secured to a drill bit or earth-boring tool and a hammer movably disposed relative to the anvil so as to strike repeated downwardly directed impacts against the anvil, to thereby drive the bit or cutting tool through the earth formations. These tools vary widely in their efiiciency, that is, in making most effective use of the energy in the power fluid to maximize the impactive energy of the hammer.

It is, therefore, a primary object of this invention to provide a percussion-type drill having improved features of construction adapted to provide a drill which is of relatively simple but rugged construction, and which is exceptionally efiicient in operation.

An important object is to provide a percussion-type drill employing pneumatic power fluid and adapted to deliver maximum energy from the power fluid to the percussion stroke.

Another object is the provision of a novel valve arrangement for controlling the flow of pressure fluid so as to maximize the energy applied to the percussion stroke while reducing the pressure required for effecting the return stroke of the hammer element of the tool.

A more specific object is to provide a highly efiicient form of valve for pneumatic-pressure actuated percussion drills.

Otherand more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful embodiment in accordance with this invention.

In the drawing:

FIGS. 1A and 1B, together, comprise a longitudinal sectional view through a tool in accordance with one embodiment of this invention, the hammer element being shown in the position occupied at completion of a percussion stroke;

FIGS. 2 and 3 are cross-sectional views taken generally along lines 2.2 and 3-8, respectively, of FIG. 1A.

FIG. 4 is a cross-sectional view taken generally along line 44 of FIG. 13;

FIG. 5 is a view similar to FIG. 1A, showing the hammer element at substantially the completion of its return stroke;

FIG. 6 a view similar to FIG. 5, showing the hammer element at the position occupied at an early stage in the percussion stroke;

FIG. 7 is an exploded perspective view of the valve elements of the tool; and

FIG. 8 is an enlarged elevational View of the valve.

Referring to the drawing, the tool comprises a generally tubular barrel 10 having an axial bore 11, and is provided at its lower end with an externally threaded pin member 12 which is threadedly received in an internally threaded box 13 provided in the upper end of a tubular coupling 14 somewhat larger in external diameter than the external diameter of barrel 10, thereby providing the annular upwardly facing external shoulder 15 about the exterior of the lower end of barrel 10. At its upper end barrel 10 is provided with an internally threaded socket 16 which is ICE adapted to receive an externally threaded pin '17 formed on the lower end of a tubular drill head 18- somewhat larger in external diameter than barrel 10. The enlarged diameter of drill head 18 provides the downwardly facing annular shoulder 19 about the upper end of barrel 10. A tubular casing 20 is mounted about the exterior of barrel 10 and is securely clamped in position about the barrel between shoulders 15 and 19 when the tool is assembled. Drill head 18 has an internally threaded socket 21 at its upper end adapted to receive the externally threaded pin 22 on the lower end of the tubular drill stem 23, having an axial bore 24 which is in communication with an axial bore 25 extending through the drill head and communicating with the interior of barrel 10. The

bottom of socket 16 is counterbored to provide an up wardly facing annular shoulder 26 which forms a seat for a valve mechanism, designated generally by the numetal 27, the valve mechanism being held in place against seat 26 by the inner end of pin 17 of the drill head when the latter is screwed down into socket 16.

. Slidably disposed in the bore of barrel 10, below the valve mechanism 27, is a generally cylindrical anvil 2%. An intermediate portion of the latter is provided with longitudinal splines 30 (see FIG. 4) which engage corresponding spline grooves 3 1 formed in the bore wall of coupling 14, whereby to permit longitudinal movement of the anvil relative to the barrel while preventing relative rotation therebetween. At its lower end anvil 28 is provided with an internally threaded socket 32 adapted to receive the threaded shank 33- of a percussion bit 34 which may be of any generally conventional construction. An axial bore 35 extends through anvil 2.8 from a point spaced a short distance from the upper end thereof to its lower end where it is adapted to communicate with aregistering bore 36 extending through the body of bit 34 and communicating with discharge orifices 37 for exhausting fluid from the bit. Anvil 28 is provided with a plurality of radial ports 38.0ornmunicating the upper end of bore 35 with the interior of barrel Ill, the ports opening to a clearance space 39 between an upper portion 28a of the anvil, which is reduced somewhat in diameter to provide the annular clearance space 39' between portion 28a and the bore wall of barrel 10. An annular enlargement 40 is provided about reduced diameter portion 2.8a intermediate ports 38 and the upper end of the anvil and functions as a slidable closure for annular space 3-9.

The lower end of coupling 14 is provided with a reduced diameter externally threaded pin 44 which is received in an internally threaded socket 45 provided in the upper end of a tubular extension sleeve 46 having an internal bore 47 somewhat larger than the external diameter of splines 30, bore 47 being further restricted at its lower end to provide an axial opening 48' adapted to closely receive the exterior of the anvil. The reduction in diameter of opening 48 relative to bore 47 provides an upwardly facing annular shoulder 49 about the exterior of the anvil. A seal ring 5'0 is mounted in the wall of opening 48 to form a slidable fluid-tight seal between the lower end of extension sleeve 46 and the exterior ofthe anvil. The upper ends 51 of splines 30 extend radially outwardly beneath the lower end of pin 12 and by engagement with the latter serve to limit upward movement of the anvil relative to barrel 10. The lower endsSZ of the splines are adapted to engage shoulder 49 in the lower end of sleeve 46 to thereby limit downward movement of the anvil relative to the barrel. v

The exterior of barrel 10 is planed off longitudinally at substantially intervals to provide two pairs of flats 6tl60 and 61-61 on diametrically opposite sides of the barrel, the fla-ts being separated by the rounded corners 62 forming portions of the external periphery of the barrel. The flats so-provided on the exterior of the barrel cooperate with the surrounding wall of casing to define longitudinal passages 63-63 and 64-64 therebea tween, whilethe round portions 62 of the barrel, which have close fitting engagement with the inner wall of casing 20, form seals preventing communication between adjacent passages '63 and 64. To assure fluid-tight seals between the rounded portions 62 and the wall of casing 20, the latter is dimensioned to form a press-fit about the exterior of barrel 10. Passages 64-64 extend longitudinally from a point just above pin 12 to a point below shoulder 26 in the barrel, as best seen in FIGS. 1A and 5. Passages 63-63 extend longitudinally from a point somewhat above the lower ends of passages 64 to a point just below the inner end of pin 17, as best seen in FIG. 6.

Three sets of longitudinally spaced ports 70, 71 and 72 provide communication between passages 64 and the interior of barrel 10. Ports 70 and 72 are located near the upper and lower ends cr -passages 64, while ports 71 are located at an intermediate point along the wall of the barrel. Two pairs of ports 73 and 74 (FIG. 6) provide communication between the upper and lower ends of passages 63'and the interior of barrel 10.

A generally cylindrical piston orhammer element 75 is slidably mounted in bore 11 of barrel 10, having a close sliding fit therein, and is adapted to reciprocate in the barrel to eitect impactive engagement with the upper end of anvil 28 in response to the flow of pneumatic fluid through the several passages and ports under the control of valve mechanism 27.

Valve mechanism 27 comprises a valve cage 80 which includes a base ring 81 having an axial port 82 therein, base ring 81 being adapted to fit on seat 26 in the bot-. tom of socket 16. Intermediate the inner and outer periphery or base ring 81, cage 80 is provided. with an upstanding annular flange 83 having a plurality of radial openings 84'therethrough. Flange 83, being spaced inwardly from the outer periphery of base ring 81, de' fines an annular space 85 between the outer periphery of flange 83 and the inner wall of socket 16. Mounted on top of flange 83 is a cap 86 which is held in place on the cage by the inner end of pin 17 of the drill head when the latter is screwed down into socket 16, thereby securing-the valve mechanism firmly against seat 26. Cap

. 26 is provided with a plurality of passages 87 which extend transversely across the cap and communicate at their outer ends with ports 73 (FIG. 6).. A cylindrical recess 88, co-axial with port 82, provides communication between the several passages 87 and the interior of flange 83, the inner edge of recess 88 defining a valve seat 89, while the opposed inner edge of port 82 defines a valve seat 90a Cap 86 is also provided on opposite 'sides thereof, at .substantially'right angles to the direction of passages 87, with a plurality of vertically extending passages 91 which provide communication through the cap between bore of the drill head and annular-space 85, and thence through radial openings 84 and port 82 with the interior of barrel 10, or through recess 88 and passages 87 with ports 73. and passages 63, depending on the position of a valve 92. v V 7 Valve 92 is of aspecialized structure which contributes most significantly to the efiiciency of the'drill. As best seen vin FIG. 8, the valve body'is a generally circular disk Diameter at leading edge 93 inch 1.000 Thickness of leading edge 93 do 1/32 Total thickness of valve .do -1/32 Axial thickness-surface 94 do 3/64 Axial thickness-surface 95 do 9/64 Angle a (FIG. 8) degree 51.5 Angle b (FIG. 8) do 16.7

In operation, pneumatic fluid, such as compressed air or gas, will be delivered through the bores of drill stem 23 and of drill head 17 through passages 91 and ports 84 into a the interior of the valve cage. With the valve in the down position (FIG. 1A) closing port 82 and the hammer at the bottom of its impactive stroke, the pneumatic fluid under pressure will be directed through passages 87 and ports 73 into passages 63, from which the pressure fluid will enter the bore of barrel 10 through ports 74 into mounted in the bore of flange 83 for vertical movement between seats 89, and 90. The valve has a peripheral edge 93 which is generally V-shaped in longitudinal section, being defined byconverging upper and lower tapered surfaces 94 and 95,- respectively. Edge 93 has "a'diameter providing a close butfree fit within the bore of flange 83 and is located non-symmetrically'with'respect tothe ends ofthe valve, being oif-set slightly toward the ,upper end. The thickness of valve 92 fromend-to-end is made appreciably less than the diameter of ports 84, so that when the valve is in engagement with either seat 89 or 90,- edge 93, which is termed the leading edge forpurclearance space 39 above shoulder 40 and exert upward pressure on the lower end ofhammer element 75, driving the latter upwardly in its return stroke. As the latter passes ports 71, the pressure fluid beneath the hammer element is exhausted to passages 64 and thence through 7 ports 72 and 38 into passages 35 and 36 and thence through outlets 37 from the bit. At the same time, the inertia of the hammer element continues to move the hammer element upwardly until it closes ports 70 and pressure fluid trapped between the upper end of the hammer element and the valve cage will be compressed by this continuing upward movement of the hammer element. This pressure momentarily becomes greater than the pressure inside the valve cage above valve 92 and forces the valve upwardly against seat.89, thereupon closing off passages 87. Leadpower is thus maintained until the hammer element passes ports 70, whereupon'the pressure fluid will be vented into passages 64 whence it will flow through ports 72 and 38 and passages 35 and 36 to hit outlets 37. As the hammer moves downwardly past ports 71, on the continuation of its down stroke, pressure fluid will be compressed between the lower end of the hammer and the upper end of anvil 28, thereby forcing the pressure fluid back through ports 74 and passages 63 to passages 87, so as to build up pressure on top of valve 92, which, at that moment, is in its elevated position against seat 89, and finally forcing the valve back .downto its original position on seat to complete the cycle. i" I V By positioning leading edge 93 of the vale so that it will be slightly above the center of ports 84 and by offsetting the leading edge toward the upper end of th'e valve body, the valve will be dyhamically unstable and tend to drop from its uppermost position. At the same time, by' its taper, surface acts as an :airfoil'in response to the flow of air across this surface to produce anegative lifit or suction on the valve, which, together with the unbalanced character of the valve, will icauselthe valve to fall to its down position the ext-ention of an absolute minimum of pressure onits'upper' end. i i i v Since thesefeatures of construction of the valve result in a minimum of pressure required to close the valvej that is, tomove it to its down position, the amount of compression required iby the hammer element at the bottom of its stroke will "be a' minimum and thereby'produce a lesser cushioning action at the bottom of the down stroke, thereby enabling the hammer to deliver maximum impactiveenergy to the anvil; r

The air delivered through exhaust ports 71 and 72and discharged through the bit outlets will aid in removing cuttings by blowing them back upwardly through the drill hole.

The sliding connection formed between sleeve 46 and anvil 28 as limited by shoulders 51 and 52, permits relative longitudinal movement between the anvil carrying the bit and the casing of the drill, as may necessarily occur during operation of the drill.

It will be understood that instead of the percussion-type bit illustrated in FIG. 1B, a rotary-type bit may be secured to the lower end of anvil 28 and percussive force supplied thereto while the drill string is rotated to increase the cutting action of the rotary-type bit.

It will be understood that various changes and modifications may be made in the details of the illustrative embodiments within the scope of the appended claims, but without departing from the spirit of this invention.

What I claim and desired to secure by Letters Patent is:

1. In an earth-boring drill, the combination comprising a tubular body having an axial bore, an anvil member mounted -for limited longitudinal movement in the lower end of said bore and adapted to be secured to an earthcutting bit member, a hammer member reciprocable in said bore relative tothe anvil member for percussive engagement therewith, a valve chamber in the upper end of said bore, inlet port means extending radially through the wall of said chamber providing communication between the interior thereof and a source of pneumatic pressure fluid, first outlet port means at one end of said chamber below said inlet port means commumcating with the interior of said bore above said hammer member, second outlet port means from the chamber above said inlet port means and coaxial with said first outlet port means, passage means connecting said second outlet port means with the interior of said bore at a level below that attained by the lower end of the hammer member in its downward travel, exhaust ports from said bore at longitudinally spaced points along the path of movement therein of said hammer member, and disk-shaped valve means horizontally disposed in said chamber for vertical movement between positions opening and closing the respective outlet port means and operable in response to reciprocation of the hammer member to direct pneumatic fluid from said inlet port means alternately to said first and second outlet port means, and valve means being dynamically unbalance-d in the direction of said first outlet port means.

in an earth-boring drill, the combination comprising a tubular body having an axial bore, an anvil member mounted for limited longitudinal movement in the lower end of said bore and adapted to be secured to an earthcutting bit member, a hammer member reciprocable in said bore relative to the anvil member for percussive engagement therewith, a valve chamber in the upper end of said bore, inlet port means extending radially through the wall of said chamber providing communication between the interior thereof and a. source of pneumatic pressure fluid, first outlet port means at one end of said chamber below said inlet port means communicating with the interior of said bore above said hammer member, second outlet port means from the chamber above said inlet port means and coaxial with said first outlet port means, passage means connecting said second outlet port means with the interior of said bore at a level below that attained by the lower end of the hammer member in its downward travel, exhaust ports from said bore at longitudinally spaced points along the path of movement therein of said hammer member, and valve means movable in said chamber between said outlet port means and operable in response to reciprocation of the hammer member to direct pneumatic fluid from said inlet port means alternately to said first and second outlet port means, said valve means comprising a circular valve body horizontally dis osed in said chamber, said-valve body having a peripheral edge generally V-shaped in vertical cross-section and axially oil-set toward the upper end of the valve body, the upper and lower ends of the valve body defining closures respectively for said second and first outlet port means.

3. In an earth-boring drill, the combination comprising a tubular body having an axial bore, an anvil member mounted for limited longitudinal movement in the lower end of said bore and adapted to be secured to an earth-cutting bit member, a hammer member reciprocable in said bore relative to the anvil member for percussive engagement therewith, said body having fiuid passage means for conducting pressurized fluid from a source into and out of opposite ends of said bore for reciprocating said hammer member, and valve means mounted in the upper end of said bore for alternately directing said pressurized fluid into the passage means leading into opposite ends of said bore in response to reciprocation of said hammer member, said valve means comprising a tubular cage coaxial with said bore and having a plurality of radial passages through the wall thereof, a lower end wall on said cage having a first axial outlet port communicating with the upper end of the bore, a circular cap mem ber closing the upper end of said cage, said cap member having a first passage means therethrough providing communication between said source of pressurized fluid and the outer ends of said radial passages, a second outlet port in said cap member oo-axial with said first outlet port and vertically spaced therefrom, said cap member having second passage means providing communication between said second outlet port and the passage means in said body leading to the lower end of said bore, and a valve member mounted in said valve cage for movement alternately into and out of closing engagement with said first and second outlet ports in response to reciprocation of said hammer member, said valve member comprising a circular diskshaped body horizontally disposed in said cage, said body having a peripheral edge V-shaped in axial section and offset toward the upper end of :the body.

4. In an earth-boring drill, the combination comprising a tubular outer casing, a tubular inner barrel coaxially mounted within the casing, an anvil member mounted for limited longitudinal movement in the lower end of the barrel and adapted to be secured to an earth-cutting bit member, a hammer member reciprocable in the bore of the barrel above the anvil member for percussive engagement therewith, a valve cage mounted in the upper end of said barrel, inlet port vmeans through the wall of the cage providing communication between the interior thereof and a source of pneumatic pressure fluid, first outlet port means at one end of said cage below said inlet ports communicating with the interior of said barrel above said hammer member, second outlet port means from the cage above said inlet port means, first passage means defined between the outer casing and said barrel connecting said second outlet port means with the interior of the barrel at a level below that attained by the lower end of the hammer member in its downward travel, exhaust ports through the wall of said barrel communicating with the interior thereof at longitudinally spaced points along the path of movement therein of said hammer member, second passage means defined between the casing and the barrel connecting said exhaust ports, and valve means mounted in said cage operable by the reciprocation of the hammer member to alternately direct pneumatic fluid to said first and second outlet port means,

said valve means being dynamically unbalanced in the direction of said first outlet port means.

5. The combination as defined in claim 4, wherein said valve means comprises a circular disk-shaped body horizontally disposed in said cage for axial movement into and out of closing engagement with the respective outlet port means, said valve body having a peripheral edge V-sh-aped in axial section and oifset toward the upper end of the valve body, the opposite ends of said valve body defining closures for the respective outlet port means.

6. Avalve-and-cage construction for pneumatic motors, References Gated in the fileof this patent comprising, a generally tubular cage having longitudinally UNITED STATES PATENTS spaced coaxial outlet ports, and having inlet ports communicating with the interior nf'the cage through the 1,924,812 Shag 29, 1933 wall thereof at points intermediate the outlet ports, and 5 2,885,004 MQTIiSOII M y 19 9 a valve member movable in said cage, said valve member ,9425 79 Morrison June 28, 1960 comprising a disk-shaped body horizontally disposed in said cage for axial movement into and out of closing en- FOREIGN PATENTS gagement with the respective outlet ports, said valve 33 742, Sweden APR 23, 5 body having a peripheral edge V-shaped in axial section 10 55 Great Britain May 5, 1921 and ofieet toward one end of the valve body to dynami- 97,482 Switzerland Feb 1 1923 cally unbalance the valve member, the opposite ends of said valve body defining closures for the respective outlet ports. 

